[clang] Stop providing builtin overload candidate for relational function pointer comparisons

Word on the grapevine was that the committee had some discussion that
ended with unanimous agreement on

[clang] Stop providing builtin overload candidate for relational function pointer comparisons

Word on the grapevine was that the committee had some discussion that
ended with unanimous agreement on eliminating relational function pointer comparisons.

We wanted to be bold and just ban all of them cold turkey.
But then we chickened out at the last second and are going for
eliminating just the spaceship overload candidate instead, for now.

See D104680 for reference.

This should be fine and "safe", because the only possible semantic change this
would cause is that overload resolution could possibly be ambiguous if
there was another viable candidate equally as good.

But to save face a little we are going to:
* Issue an "error" for three-way comparisons on function pointers.
But all this is doing really is changing one vague error message,
from an "invalid operands to binary expression" into an
"ordered comparison of function pointers", which sounds more like we mean business.
* Otherwise "warn" that comparing function pointers like that is totally
not cool (unless we are told to keep quiet about this).

Signed-off-by: Matheus Izvekov <[email protected]>

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D104892

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Fix crash and rejects-valid when a later template parameter or default
template argument contains a backreference to a dependently-typed
earlier parameter.

In a case like:
template<typename T, T A

Fix crash and rejects-valid when a later template parameter or default
template argument contains a backreference to a dependently-typed
earlier parameter.

In a case like:
template<typename T, T A, decltype(A) = A> struct X {};
template<typename U> auto Y = X<U, 0>();
we previously treated both references to `A` in the third parameter as
being of type `int` when checking the template-id in `Y`. That`s wrong;
the type of `A` in these contexts is the dependent type `U`.

When we encounter a non-type template argument that we can't convert to
the parameter type because of type-dependence, we now insert a dependent
conversion node so that the SubstNonTypeTemplateParmExpr for the
template argument will have the parameter's type rather than whatever
type the argument had.

llvm-svn: 363972

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Move the warning about unused relational comparison from -Wunused-value to
-Wunused-comparison. Also, newly warn on unused result from overloaded
relational comparisons, now also in -Wunused-compari

Move the warning about unused relational comparison from -Wunused-value to
-Wunused-comparison. Also, newly warn on unused result from overloaded
relational comparisons, now also in -Wunused-comparison.

llvm-svn: 203535

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PR16074, implement warnings to catch pointer to boolean true and pointer to
null comparison when the pointer is known to be non-null.

This catches the array to pointer decay, function to pointer dec

PR16074, implement warnings to catch pointer to boolean true and pointer to
null comparison when the pointer is known to be non-null.

This catches the array to pointer decay, function to pointer decay and
address of variables. This does not catch address of function since this
has been previously used to silence a warning.

Pointer to bool conversion is under -Wbool-conversion.
Pointer to null comparison is under -Wtautological-pointer-compare, a sub-group
of -Wtautological-compare.

void foo() {
int arr[5];
int x;
// warn on these conditionals
if (foo);
if (arr);
if (&x);
if (foo == null);
if (arr == null);
if (&x == null);

if (&foo); // no warning
}

llvm-svn: 202216

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sizeof(void) etc. should be a hard error in C++.

PR16872.

llvm-svn: 188324

Bound member function diagnostic - suggest no-args calls and note overload candidates

Still missing cases for templates, but this is a step in the right
direction. Also omits suggestions that would

Bound member function diagnostic - suggest no-args calls and note overload candidates

Still missing cases for templates, but this is a step in the right
direction. Also omits suggestions that would be ambiguous (eg: void
func(int = 0); + void func(float = 0); func;)

llvm-svn: 183173

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Add notes for suppressing and (if it's a zero-arg function returning bool) fixing the function-to-bool conversion warning.

llvm-svn: 146280

Add a warning for implicit conversion from function literals (and static
methods) to bool. E.g.

void foo() {}
if (f) { ... // <- Warns here.
}

Only applies to non-weak functions, and does not apply

Add a warning for implicit conversion from function literals (and static
methods) to bool. E.g.

void foo() {}
if (f) { ... // <- Warns here.
}

Only applies to non-weak functions, and does not apply if the function address
is taken explicitly with the addr-of operator.

llvm-svn: 145849

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Update all tests other than Driver/std.cpp to use -std=c++11 rather than
-std=c++0x. Patch by Ahmed Charles!

llvm-svn: 141900

Catch placeholder types in DefaultLvalueConversion
and DefaultFunctionArrayLvalueConversion. To prevent
significant regression for should-this-be-a-call fixits,
and to repair some such regression fr

Catch placeholder types in DefaultLvalueConversion
and DefaultFunctionArrayLvalueConversion. To prevent
significant regression for should-this-be-a-call fixits,
and to repair some such regression from the introduction of
bound member placeholders, make those placeholder checks
try to build calls appropriately. Harden the build-a-call
logic while we're at it.

llvm-svn: 141738

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Treating the unused equality comparisons as something other than part of
-Wunused was a mistake. It resulted in duplicate warnings and lots of
other hacks. Instead, this should be a special sub-categ

Treating the unused equality comparisons as something other than part of
-Wunused was a mistake. It resulted in duplicate warnings and lots of
other hacks. Instead, this should be a special sub-category to
-Wunused-value, much like -Wunused-result is.

Moved to -Wunused-comparison, moved the implementation to piggy back on
the -Wunused-value implementation instead of rolling its own, different
mechanism for catching all of the "interesting" statements.

I like the unused-value mechanism for this better, but its currently
missing several top-level statements. For now, I've FIXME-ed out those
test cases. I'll enhance the generic infrastructure to catch these
statements in a subsequent patch.

This patch also removes the cast-to-void fixit hint. This hint isn't
available on any of the other -Wunused-value diagnostics, and if we want
it to be, we should add it generically rather than in one specific case.

llvm-svn: 137822

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Simplify calling CheckPlaceholderExpr, converge on it in a few places,
and move a vector-splat check to follow l-value conversion.

llvm-svn: 129254

Basic, untested implementation for an "unknown any" type requested by LLDB.
The idea is that you can create a VarDecl with an unknown type, or a
FunctionDecl with an unknown return type, and it will

Basic, untested implementation for an "unknown any" type requested by LLDB.
The idea is that you can create a VarDecl with an unknown type, or a
FunctionDecl with an unknown return type, and it will still be valid to
access that object as long as you explicitly cast it at every use. I'm
still going back and forth about how I want to test this effectively, but
I wanted to go ahead and provide a skeletal implementation for the LLDB
folks' benefit and because it also improves some diagnostic goodness for
placeholder expressions.

llvm-svn: 129065

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Clean up our handling of template-ids that resolve down to a single
overload, so that we actually do the resolution for full expressions
and emit more consistent, useful diagnostics. Also fixes an IR

Clean up our handling of template-ids that resolve down to a single
overload, so that we actually do the resolution for full expressions
and emit more consistent, useful diagnostics. Also fixes an IRGen
crasher, where Sema wouldn't diagnose a resolvable bound member
function template-id used in a full-expression (<rdar://problem/9108698>).

llvm-svn: 127747

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